Wrenchless collect for surgical blade

ABSTRACT

A wrenchless collet for attaching a surgical saw blade to an oscillating handpiece. The collet is provided within a housing attached to the handpiece and contains a clamping means for holding the blade and a bi-stable operating mechanism capable of holding the clamping means in either an open position to receive the blade or in a closed position to hold the blade for use with the handpiece. The bi-stable operating mechanism is activated into either position by simply being pushed in one direction or another. In one embodiment, the bi-stable operating mechanism comprises a shaft which may be positioned to one axial extreme or the other and which is held in the chosen position by a spring which frictionally engages the collet housing to maintain the clamping means in either an open or closed position.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to blade attachment mechanisms forsurgical saws. More particularly, the invention relates to wrenchlesschuck or collet which can secure a surgical device such as a saw bladeto a drive means without any additional tools.

2. Description of the Prior Art

It is often necessary to use powered tissue cutting tools in order toperform surgical procedures. Such tools generally comprise a handpiecewhich cyclically moves a tissue cutting device such as a blade or burrin some oscillating or reciprocating manner. The handpiece generallyincludes a pneumatic or electric drive motor having an output shaft towhich the cutting device is attached, the shaft being axially alignedwith a drive axis of the handpiece. As used herein, the term "driveaxis" refers to the axis of the motor output shaft through which poweris delivered from the motor. The handpiece may be a "pencil" typehandpiece in which the body is elongated and the drive axis is alignedwith the axis of the body or a pistol-grip type of handpiece in whichthe drive axis is aligned in a chosen direction relative to the grip.The drive motor of the handpiece produces a driving force whichreciprocates the output shaft and cutting device either longitudinally,i.e. linearly along the drive axis (like a saber saw), or arcuately in aplane perpendicular to the drive axis. Handpieces utilizing the formertype of action are generally referred to as reciprocating saws whilethose utilizing the latter action are generally referred to asoscillating saws. In some cases an oscillating saw may transfer theoscillating drive motion so that it is cyclical within a plane parallelto the axis of the elongated body of the handpiece. A sagittal saw is atype of oscillatory saw in which the cyclical reciprocating action is ina plane aligned with the drive axis.

In all instances, numerous tissue cutting blades or burrs or otherdevices (all collectively referred to herein as "blades") are adapted tobe secured to the handpiece via a chuck or collet mechanism which isutilized to selectively attach and release a desired blade. A variety ofdifferent cuts can be made with a single saw depending upon the shape ofthe blade. For oscillating saws, the blades are often in the form of aflat, elongated body having a cutting edge (e.g. teeth, abrader, etc.)at one end and a hub at the other end, the hub being shaped and adaptedto fit the particular collet. Such flat blades are used to make cuts ina plane perpendicular to the drive axis. An oscillating saw may also beused for effecting cuts in a plane parallel to the handpiece axis byattaching a transverse hub to a flat blade.

Many blade collets utilize a threaded stud axially extending from theoutput shaft and a nut adapted to engage the stud to clamp the blade hubto the handpiece. These collets generally require the use of a separatewrench to turn the clamping nut. U.S. Pat. No. 5,237,884 (Seto) shows avariety of conventional tool-requiring chuck mechanisms in the form of athreaded shaft which is turned to tighten against a clamping plate andsaw blade. Since it is desirable to avoid extra tools in a surgicalsetting, some collets eliminate the need for a separate tool byutilizing a nut (e.g. a wingnut) that can be manipulated without tools.Other collet designs utilize a spring actuated, longitudinally movableclamping head having longitudinally extending locking pins forengagement with corresponding holes in the blade hub. The clamp head insuch designs is movable to place the collet into an open position forreceiving a blade and into a closed position for clamping the bladebetween the head and a base surface. Such designs are referred to hereinas "wrenchless" designs and are generally preferable to other chuck orcollet mechanisms which require the use of separate tools. The terms"chuck" and "collet" are used interchangeably herein.

Yet another wrenchless collet design utilizes a spring actuated clampingplate to frictionally engage a surgical blade. In many cases projectinglocking pins extend from a clamping surface to produce a positiveengagement with holes in the blade. The blade clamp is momentarilymovable by manual pressure directed to compress the spring to an openposition for receiving a blade. Release of the manual pressure enablesthe spring to close the clamp. Such collets are difficult to clean andsterilize due to the need for the spring to be manually held in acompressed position while a blade is inserted or removed or when thecollet is cleaned.

U.S. Pat. No. 5,265,343 (Pascaloff), assigned to the assignee hereof,discloses a bi-stable type of wrenchless collet which enables the bladeclamp to stay in the open or closed position. The ability to stay openwithout manual pressure facilitates the loading, cleaning andsterilization of the device. However, this design does not easily lenditself to all types of surgical saws or to miniaturization. Accordingly,there is a need for a bi-stable wrenchless collet adaptable to smallsurgical instruments.

In the case of oscillating or sagittal surgical saws used withconventional flat blades oscillating in a plane aligned with or parallelto the axis of a pencil-type handpiece, the collet mechanism must beadapted to apply a force to the blade hub in a direction perpendicularto the handpiece axis. For microsurgical procedures such asoral-maxillofacial, ear-nose-throat (ENT) and other procedures inconfined areas, the size of the collet must be minimized as much aspossible to improve the surgeon visualization of the surgical site. Thechallenge is to provide as small a collet as possible while providing asmuch blade holding force as possible while also enabling the collet tostay open for sterilization or loading.

A wrenchless collet chuck in the form of a pushbutton is shown in U.S.Pat. No. 5,383,785 (Brugger) as part of a dental tool. The collet chuckis a hollow cylindrical member with axial slots spaced along the body ofthe member such that adjacent slots are open at opposite ends of themember in an alternating pattern. The arcuate portions of thecylindrical member between the slots act as clamping elements forholding a tool in axial alignment with the hollow cylinder. A conicalcontrol surface is moved by the pushbutton to move the clamping elementsradially. This device is, however, not only unsuitable for holdingblades perpendicular to the chuck axis but is also unable to maintain anopen position without a user having to continually push and hold thebutton open.

Another representative wrenchless collet is shown in U.K. PatentApplication 2,195,274. This device utilizes a plurality ofcircumferentially arranged locking balls which are biased radiallyinwardly against an axially aligned tool shaft.

It is an object of this invention to provide a blade collet that doesnot require a separate tool for its operation.

It is another object of this invention to produce a wrenchless colletfor holding a surgical device to a drive mechanism.

It is a further object of this invention to produce a wrenchless bladecollet for holding a flat surgical saw blade on an oscillating orsagittal saw.

It is yet another object of this invention to produce a wrenchless bladecollet having a minimal size in order to enable its use in microsurgicaldevices.

It is another object of this invention to provide a blade collet that iseasily operated and cleaned.

It is also an object of this invention to provide a wrenchless bladecollet which is bi-stable, i.e. having two states such that the colletcan be actuated to and stay in either an open position or a closedposition by a pushing motion.

It is yet another object of this invention to produce a collet systemadapted to securely hold a tissue cutting device to an oscillatory saw.

It is also an object of this invention to produce a wrenchless andadapterless system for securing a surgical blade to a powered handpiece.

It is another object of this invention to produce a system for attachingtissue cutting devices to powered handpieces without the necessity forauxiliary tools.

SUMMARY OF THE INVENTION

These and other objects of this invention are achieved by the preferredembodiment disclosed herein which is a wrenchless collet for holding acutting device comprising a blade clamp means in the form of a first,axially stationary clamping surface and a second, axially movableclamping surface. The second clamping surface is movable to either anopen position, in which it is spaced from the first clamping surface, ora closed position in which it is urged toward the first clampingsurface. A clamp holding means is provided for holding the blade clampin either the open position or the closed position, the clamp holdingmeans comprising a shaft connected to the blade clamp means and abi-stable biasing means for acting on the shaft to urge it axiallyeither in one direction when the blade clamp is in the closed positionor in the other direction when the blade clamp is in the open position.In the preferred embodiment, the bi-stable biasing means comprises aflat V-shaped spring in the form of a unitary member having a centralbight portion and a pair of spring legs extending outwardly from thebight portion. The spring is attached to the shaft so that the springlegs normally have a predetermined width greater than the diameter ofsaid shaft. The bight portion is attached to the shaft such that thespring legs lie substantially in a plane parallel to said axis. Theshaft and the spring legs slide in a bore which is sized to enable thepair of spring legs to be compressed to a width substantially equal tothe diameter of the shaft when the blade clamping means is in the openposition. A spring leg expansion means is provided for enabling the pairof spring legs to return toward their normal, unbiased state, when theblade clamp means is in the closed position.

The invention disclosed herein is also in the method of selectivelyattaching a cutting device to a surgical handpiece comprising the stepsof providing a wrenchless collet having a first clamping surface memberand a second clamping surface member, the members relatively movablebetween a closed position wherein they are aligned such that a cuttingdevice may be held between the members and an open position wherein theyare spaced and a cutting device may be inserted or removed therefrom. Aclamp holding means is provided to hold the wrenchless collet eitheropen or closed. A user accessible means is secured to the first clampingsurface member to push it either toward or away from the second clampingsurface member. The wrenchless collet is selectively opened by pushingthe user accessible means in a first direction to move the firstclamping surface member axially in one direction or selectively closedby pushing the user accessible means in a second direction to move thefirst clamping surface member axially in an opposite direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view, in cross-section, of the distal end ofa sagittal saw showing one embodiment of the invention in a closedposition.

FIG. 2 is a cross-sectional view of FIG. 1 taken along the line 2--2.

FIG. 3 is an exploded view of a component part of the embodiment of theinvention shown in FIG. 1.

FIG. 4 is a plan view of another component part of the embodiment of theinvention shown in FIG. 1.

FIG. 5 is a cross-sectional view of FIG. 4 taken along the line 5--5.

FIG. 6 is a view of FIG. 1 showing the embodiment in an open position.

FIG. 7 is a diagrammatic view in cross-section of another alternateembodiment of the invention.

FIG. 8 is a plan view of a component part of FIG. 7.

FIG. 9 is an alternate embodiment of the part shown in FIG. 8.

FIG. 10 is another alternate embodiment of the part shown in FIG. 8.

FIG. 11 is a side elevation view, in cross-section, of an alternateembodiment of the invention in an open position.

FIG. 12 is a view of FIG. 11 showing the embodiment in a closedposition.

FIG. 13 is an exploded view of FIG. 11.

FIG. 14 is a side elevation view in cross-section of another alternateembodiment of the invention in a closed position.

FIG. 15 is a view of FIG. 14 in an open position.

FIG. 16 is a diagrammatic view in cross-section of another alternateembodiment of the invention in an open position.

FIG. 17 is a view of FIG. 16 in a closed position.

FIG. 18 is a side elevation view in cross-section of another alternateembodiment of the invention in a closed position.

FIG. 19 is a view of the embodiment of FIG. 18 in an open position.

FIG. 20 is an elevation view of a component of FIG. 18.

FIG. 21 is an alternate embodiment of a spring used in the embodimentshown in FIG. 18.

FIG. 22 is a side elevation view in cross-section of another alternateembodiment of the invention in an open position.

FIG. 23 is a side elevation view in cross-section of another alternateembodiment of the invention in an open position.

FIG. 24 is a cross-section of FIG. 23 taken along the line 24--24.

FIG. 25 is a view of FIG. 24 showing the invention in a closed positionwith a blade.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIGS. 1 through 6, a wrenchless blade collet 10 constructedin accordance with the principles of this invention is mounted to thedistal end of a powered surgical handpiece 12 such as an oscillating sawor sagittal saw. Collet 10 is intended for use with a flat surgical sawblade 14 and is designed to stay in either a closed position (best seenin FIG. 1) in which it will hold blade 14 so that it may be driven in anoperative manner by handpiece 12 (i.e. in either a sagittal oroscillating mode), or in an open position (best seen in FIG. 6) toenable the blade to be assembled with or removed from the collet, or toenable the collet to be sterilized and cleaned.

Collet 10 comprises a housing 20 having an axis 21, a blade clamp 22 anda bi-stable clamp operating or holding mechanism 24 which, in the firstembodiment shown in FIGS. 1-6, is a toroidal, overcenter biasing spring26, best seen in plan view in FIG. 4. The preferred embodiment oftoroidal spring 26 comprises a single wire formed into a star-like shapehaving a plurality of lobes 70, the tips of which define an innercircular periphery 72 and an outer circular periphery 74. Depending onthe chosen design, both circular peripheries and the spring body may beconcentric and co-planar when the spring is in its neutral state or thespring body between these peripheries may be outside this plane (asdiagrammatically shown in FIG. 5). Nevertheless, the spring is intendedto exert a force in each of two states, i.e. opened and closed, and ineach of these states the collet will maintain the set position. The termbi-stable is used to indicate that the spring is able to hold the colleteither open or closed. It is not intended to mean the spring is stablein any position without cooperative action with its housing. Thus, whenplaced in one of its biased states and viewed from the side (as shown inFIG. 1) the inner circular periphery 72 is situated in one plane P1perpendicular to axis 21 while the outer circular periphery 74 issituated in another, parallel plane P2. A similar, but reversedarrangement is shown in FIG. 6 when the spring is in its other biasedstate.

Housing 20 comprises upper and lower sections 20a and 20b, respectively,situated in a bearing 27 at distal end 28 of handpiece 12, and isconnected (by means not shown) to a driver means 29 which imparts tohousing 20 (and thereby to blade 14) the appropriate oscillating drivemotion about axis 21. As best seen in FIGS. 1 and 2, housing 20 has atop clamping surface 30 provided with a plurality of annularly arrangedprojecting pins 32 intended to be received within correspondingapertures 33 in the hub or proximal end of blade 14. The pins andapertures may be circular in cross-section as shown, conical,rectilinear as shown in U.S. Pat. Des. 362,065 assigned to the assigneehereof, or may have any other suitable cross-section.

Bi-stable clamp operating mechanism 24 comprises a shaft 40 having ends44 and 48, the shaft extending through bore 42 of housing 20 to providea pushing member at each end. The shaft is provided with an enlarged,transverse clamping head 43 at end 44 and an enlarged transversepushbutton 46 at the other end 48. In the preferred embodiment, head 43is at all times parallel to surface 30 although it will be understoodthat some other relationship (e.g. conical interface, contoured, etc.)may also be used within the scope of this invention. As will beunderstood below, both the clamping head and the pushbutton serve aspushing members to alternately push shaft 40 in one axial direction orthe other. In the preferred embodiment, clamping head 43 is axiallymovable relative to the shaft axis while surface 30 is axiallystationary. The shaft and bore may be keyed or provided withnon-circular cross-sections to keep head 43 from rotating relative tosurface 30. Since pushbutton 46 is enlarged and attached to end 48, itprevents travel of shaft 40 beyond a predetermined point and makes iteasy for a user to push on shaft 40 in an activating direction alignedwith axis 21 to open the blade clamp. The large sizes of the clampinghead and the pushbutton facilitate the use of the device by providing atactile indication to enable a user to merely push the shaft at one endor the other.

Shaft 40 is provided with an inner, annular V-shaped recess in the formof groove 60 interposed between ends 44 and 48 and intended to operatewith bi-stable operating mechanism 24 by receiving the inner circularperiphery 72 of toroidal spring 26. As shown in FIG. 3, the preferredembodiment of shaft 40 is formed of two cylindrical extensions 22a and22b joined by screw 50 and defining groove 60 at their juncture.Similarly, housing 20 is provided with an outer, annular groove 62intended to receive the outer circular periphery 74 of toroidal spring26. The interior 42 between grooves 60 and 62 serves as an expansionchamber for the spring and its shape is somewhat dependent upon thecharacteristics of spring 26. The diameters of grooves 60 and 62 arechosen such that spring 26 can maintain a biasing force on groove 60and, therefore, on shaft 40. This force must be sufficient to bias shaft40 downwardly in a closed position as shown in FIG. 1 to thereby urgeclamping member 43 towards clamping surface 30 to thereby retain it andblade 14 adjacent posts 32 and surface 30. Similarly, when the clamp isopened, the force must be enough to hold it open as shown in FIG. 6. Theinteraction of the spring and its associated structures serves toselectively transfer and direct the spring force to the shaft andultimately to the clamping surfaces. It will be understood that astransverse pushbutton end 46 is pushed upwardly relative to FIG. 1 tothe position shown in FIG. 6, the force of toroidal spring 26 will beovercome and it will be compressed over its neutral "center" position.At that point, the spring force is redirected to place the spring intothe position shown in FIG. 6 in which it will bias shaft 40 upwardly tokeep clamping surface 43 spaced from clamping surface 30, therebyholding blade clamp 22 in an open position.

The inner surface 80 of pushbutton 46 may be provided with a roughenedsurface such as a plurality of projections 82 which facilitate thesterilization of collet 10 in the open position. The projections areonly shown by way of example in FIG. 1 while FIGS. 3 and 5 show surface80 as being flat, albeit recessed from an annular lip 84 which may haveradially extending channels therethrough (not shown).

Another simplified variation of the previous embodiment is shown in FIG.7 as collet 90 employing a toroidal, overcenter spring 92 having twostable states, best seen in phantom in FIG. 7. Collet 90 differs fromcollet 10 in that it is housed in a unitary housing and the junctionbetween the shaft and spring is assembled differently. Spring 92 is aformed wire similar in function to spring 26 and having similar innerand outer circular peripheries, but with a different profile in planview, as best seen in FIG. 8. The radially outward arcuate segments 94enable use of complementarily shaped spaced arcuate apertures (notshown) within the groove 96 in the wall of housing 98 rather than acontinuous groove similar to groove 62 of FIG. 1. An alternateembodiment of spring 92, shown in FIG. 9 as spring 92a, is formed of aunitary piece of material having a central bore 99 which defines theinner periphery. FIG. 10 shows another spring 92b formed of amulti-coiled, single piece of wire. In operation, the clamp head 97 ofcollet 90 is held open, when spring 92 is biased to one of its bi-stablestates A, and closed when the spring is in the other of its bi-stablestates B. Both states are shown in phantom while an unstable, transitionposition of spring 92 is shown in full lines. The shape of the springbody in these views is merely intended to show that the spring shapechanges as the shaft is moved, and is not intended to be an exactdepiction of spring shape.

As shown in FIGS. 11, 12 and 13, an alternate embodiment of theinvention comprises a wrenchless collet 100 attached to the distal endof a surgical handpiece 110 having an oscillating drive member 112.Collet 100 is similar in function to collet 10 and differs in theembodiment of the invention by which the blade clamp is held in eitherthe open or closed position.

Collet 100 comprises a housing 120 having an axis 121, a bi-stable bladeclamp 122 and a dual-action, rolling member retaining mechanism 124.Housing 120 has upper and lower portions 120a and 120b, respectively,each of which has longitudinally extending cylindrical walls 130a and130b, respectively. Upper housing section 120a is provided with a flange150 and lower housing section 120b is provided with a flange 152, bothflanges serving to retain a spring 154 therebetween. In the embodimentshown, rolling member retaining mechanism 124 utilizes spherical membersrather than cylindrical members and comprises a cylindrical ball carrier126 formed integrally with lower housing 120b, surrounding shaft 140 andretaining a plurality of circumferentially spaced locking balls 128. Theradial thickness of the cylindrical wall 130a of ball carrier 126 issubstantially equal to the size of the annular gap between shaft 140 andthe cylindrical wall 130b of upper housing portion 120a. Shaft 140 has afirst annular groove 142 into which balls 128 are partially receivedwhen the blade clamp is in its closed position (FIG. 12) and wall 130bhas a second annular groove 144 into which balls 128 are partiallyreceived when the blade clamp is in its open position (as best seen inFIG. 11). It will be noted that annular groove 142 has two oppositelyfacing, axially spaced tapered side surfaces such that any axial forceimparted by balls 128 to the tapered surfaces will move the shaftaxially. Groove 144 also has two oppositely facing tapered side surfacesto receive the balls 128 and transfer compressive force from the housingto the shaft. It will be noted that lower housing portion 120b travels apredetermined axial distance between the open and closed positions inorder to accommodate the rolling motion of balls 128. The diameter ofeach of the locking balls 128 is substantially equal to (or onlyslightly greater than) the size of the spaces within which the balls areintended to move. Thus, at one extreme of axial motion as shown in FIG.12 the diameter of the locking balls is equal to the distance betweenthe radially innermost side of wall 130b and the floor of annular groove142. As the lower tapered surface of groove 142 pushes the ball upwardlyin the process of moving collet 100 from the closed position to the openposition shown in FIG. 11, the ball rolls within the space between theradially innermost side of wall 130b and the floor of annular groove 142until it clears the lower edge of annular groove 144. At this point, theball naturally rolls into this groove as the shaft is moved further intothe open position until the locking balls are captured between the floorof annular groove 144 and the radially outermost surface of shaft 140 asshown in FIG. 11. The frictional engagement at this point maintains thecollet in an open position.

The grooves 142 and 144 may be replaced by one or more coplanar recesses(not shown) which are arranged angularly about axis 121 in order to bealigned to receive a locking ball associated therewith.

Another embodiment of the invention is shown in FIGS. 14 and 15 ascollet 200 which operates similarly to collet 100 except that the spring254 is located adjacent the shaft. Shaft 240 has an intermediate groove242 which receives balls 228 in the closed position. Ball carrier 226holds balls 228 and moves within the gap between shaft 240 and body 212.The latter is provided with groove 244 to receive balls 228 in the openposition.

Another embodiment of the invention is shown in FIG. 16 as collet 300shown in an embodiment adapted to axially retain an elongated shaft 302such as a drill bit or other axially elongated tool. This embodimentoperates similarly to that shown in FIGS. 14 and 15. The clampingmechanism of collet 300 provides a tool retention force in a directionperpendicular to the axis 304 of the collet shaft in order tofrictionally engage tool shaft 302 in axial alignment with the colletshaft.

Another embodiment of the invention is shown in FIGS. 18 through 21 ascollet 400 comprising blade clamp 401, shaft 402 and spring 404. Othercomponents are similar to previous embodiments and need not beseparately explained here. Shaft 402 has cylindrical body 410, a clamphead 406 at one end thereof and a screw-receiving bore 408 at the otherend. The end of shaft 402 adjacent bore 408 is provided with atransverse axial slot 412 and the closed end of the slot is providedwith a bore 414 perpendicular to the slot. The cross-section of body 410is shaped and keyed to fit in bore 418 within which the shaft moveswithout rotation. Spring 404 comprises a flat, pre-formed spring member420 having a central bight portion 422 from which spring legs 424 and426 extend. The spring legs extend in generally the same directionrelative to bight portion 422 so spring 404 has a general "V" shape. Asimple yet effective spring 404 may be formed from a length of wireshaped to have a bight portion 422 in the form of a simple bend or withone or more coiled loops 430 as shown. Spring legs 424 and 426 canremain on the same side of the spring axis 432 from which they originate(as best seen in FIG. 18). Alternatively, an embodiment such as spring404a could be produced such that spring legs 424a and 426a extend frombight portion 422a and cross the axis 432 as best seen in FIG. 21. Bore414 is adapted to receive pin 416 which retains spring 404 withintransverse slot 412.

While spring legs 424/426 and 424a/426a are normally in a "V"configuration as best seen in FIGS. 18 and 19, the curvature of the legsmay vary from some curve as shown in FIG. 18 to fairly straight as shownin FIG. 21. The curvature of the spring legs affects the degree oftravel of shaft 402 and the clamping force. Starting from the closedposition shown in FIG. 18, it will be understood that as the pushbuttonend of the shaft 402 is pushed upwardly, the inside edges 440 and 442 ofthe housing (actually opposite sides of the bottom circular edge of bore418) push the spring legs inwardly such that when pushbutton 443 abutsthe bottom end of the housing, the radially outermost surfaces 444 and446 of spring legs 424 and 426 contact the inside wall of bore 418 asbest seen in FIG. 19. The frictional engagement at these points holdsclamp head 406 open and the curvature imparted to legs 424/426 helpsprovide this force. Similarly, starting from an open position as clamphead 406 is pushed downwardly, the contact points 444 and 446 eventuallyclear edges 440 and 442 and the natural spring force of spring 404 willassist in its further downward motion. The collet reaches its closedposition before the spring legs are able to reach their unbiased stateso the spring can continue to apply a clamping force. The curvature ofthe legs between points 444/446 and the central bight portion willaffect the speed of the spring-assisted downward motion as well as theultimate clamping force once the clamp head is closed.

Various channels and cut-outs may be provided to facilitate cleaning andsterilization. For example, an axial channel 450 may be provided in theclamp head to enable communication between slot 412 and the outsidesurface of clamp head 406. Similarly, a plurality of annularly arrangedthroughbores 452 may be situated within clamp head 406 above each pinlocation. Also, radial cut-outs 454 may be provided to access theinterior.

Another alternate embodiment of the invention is shown in FIG. 22 ascollet 600 which incorporates a modified shaft 602 having anintermediate clamp head 604 interposed between shaft ends 606 and 608.Shaft 602 is attached to a sagittal saw 607 and is adapted toreciprocate within bore 610 of housing 612 although both of theseelements are split into upper and lower portions 610a/610b and612a/612b, respectively. While previous embodiments were one-sided,single bearing designs, this arrangement enables each bore portion 610aand 610b to be provided with its own bearing 614 and 616, respectively,to more efficiently dissipate heat where high cyclical speeds arerequired. Clamp head 604 is shown in FIG. 22 in an open position spacedabove clamp surface 620 and pins 622 on drive element 624. Spring 630 issimilar to spring 404 and operates adjacent a hardened thrust collar orbushing 632 secured to rim of bore 610b adjacent the spring legs inorder to enhance performance of the invention. Spring 630 acts like thepreviously described springs of similar design to place and holdclamping head 604 in a closed position (not shown) to hold a blade (notshown) between head 604 and clamping surface 620.

A variation of this embodiment is shown in FIGS. 23-25 as collet 700attached to sagittal saw 702. The structure of collet 700 is similar tothat of collet 600 with slight variations. For example, the housingwithin which collet 700 is situated is a pair of integral extensions ofthe saw body. Collet 700 comprises a shaft 704 having an enlarged end706 and a smaller other end 708 to provide a tactile indication of whichend to push to open or close the collet. In the embodiment shown,pushing the large end opens the collet although the sizes of the endscould be reversed. Similar tactile indicators may clearly be used withall of the other embodiments disclosed herein. Shaft 704 is cylindricalwith a generally circular cross-section which has two flattened sides710 and 712, best seen in FIG. 24, which enable shaft 702 to slidewithout rotating within a generally rectangular aperture 714 in driver716. A shoulder 718 is provided to receive a similar rectangularaperture 720 in plate 722 and a threaded keeper 724 is used to secureplate 722 adjacent shoulder 718 of shaft 704. Plate 722 serves as theclamp head in this design. A pair of bearings 726 and 728 enable shaft704 to oscillate within aligned apertures 730 and 732 at the distal endof saw 702. A threaded cap 734 holds the assembly together.

As shown in FIG. 24, spring 740 is aligned in a plane transverse to theaxis of saw 702 and is supported by spring pin 742 within slot 744 ofshaft 704. A central bore 746 and aperture 748 in the keeper facilitatecleaning and sterilization of the various components. In the openposition shown in FIG. 24, the spring legs rest against bushing 750which is shaped to provide bearing points for the spring legs as thespring moves towards the closed position shown in FIG. 25. A blade 752is retained as shown when collet 700 is in the closed position.

The relative orientations of the components shown in the variousembodiments may be altered within the scope of this invention. Forexample, the spring in the embodiment of FIGS. 10 and 11 may berepositioned so that the locking balls are between the spring and theclamping head. Such changes might alter the specific function of somecomponents but would not vary the basic concept disclosed. Furthermore,other arrangements of component parts may provide further embodiments.For example, using any of the embodiments with a motion transferringlinkage to make the force of the clamping head be directed perpendicularto the axis of the shaft may enable one to produce a collet in which theactivating motion is axially aligned with the shaft while the clampingforce is perpendicular thereto, albeit applied at a point spaced fromthe axis, thereby enabling the saw blade body to be axially aligned withthe handpiece but spaced from the axis.

It will be understood by those skilled in the art that numerousimprovements and modifications may be made to the preferred embodimentof the invention disclosed herein without departing from the spirit andscope thereof.

What is claimed is:
 1. A wrenchless collet for holding a cutting devicecomprising:a housing; clamp means within said housing for holding saidcutting device, said clamp means being movable relative to said housing,having an axis and adapted to exert a clamping force on said cuttingdevice parallel to said axis and further comprising: a first, axiallystationary clamping surface; a second, axially movable clamping surface,said second clamping surface movable to either an open position in whichit is spaced from said first clamping surface or a closed position inwhich it is urged toward said first clamping surface; bi-stable clampholding means for selectively holding said clamp means in either saidopen position or said closed position comprising: a shaft connected tosaid second, axially movable clamping surface, said shaft having a firstend and a second end, said first and second ends comprising respectivefirst and second shaft pushing members; a spring biasing means forproviding a force; force transfer means for selectively directing theforce of said spring biasing means in either a first direction to holdsaid second, axially movable clamping surface spaced from said first,axially stationary clamping surface or in a second direction to holdsaid second, axially movable clamping surface adjacent said first,axially stationary clamping surface.
 2. A wrenchless collet according toclaim 1 wherein said cutting device is a flat blade having a distal endwith a cutting edge and a proximal end with a hub adapted to be retainedby said clamp means.
 3. A wrenchless collet according to claim 1 furthercomprising:said housing having a longitudinally extending openingtherethrough and said shaft extending through said opening such thatsaid first and second shaft pushing members situated respectively atsaid first and second ends of said shaft are each directly manuallyengageable such that said shaft may be alternately pushed in oppositedirections to alternately open and close said clamp means.
 4. Awrenchless collet according to claim 3 wherein one of said first orsecond ends has a different tactile indication than the other.
 5. Awrenchless collet according to claim 4 wherein said tactile indicationis sized such that one of said first or second ends is larger than theother.
 6. A wrenchless collet according to claim 1 wherein saidbi-stable clamp holding means comprises:a flat V-shaped springcomprising a unitary member having a central bight portion and a pair ofspring legs extending outwardly from said bight portion; means forattaching said flat spring to said shaft such that said spring legs liesubstantially in a plane parallel to the axis of said shaft and arecompressible and expandable toward and away from each other within saidplane; bore means within said housing coaxially situated about saidshaft adjacent said spring legs for providing a radially facing surfaceto urge said spring legs toward each other to frictionally engage saidshaft when said clamp means is in said open position; axial forcereceiving means adjacent said bore means for receiving an axiallydirected force from said pair of spring legs as they expand from eachother when said clamp means is in said closed position.
 7. A wrenchlesscollet according to claim 6 wherein said flat spring comprises at leastone coil loop at said bight portion.
 8. A wrenchless collet according toclaim 6 wherein said flat spring comprises one of said spring legsextending from that side of said bight portion which is on the same sideas said one of said spring legs.
 9. A wrenchless collet according toclaim 6 wherein said flat spring comprises one of said spring legsextending from that side of said bight portion which is on the oppositeside from said one of said spring legs.
 10. A wrenchless colletaccording to claim 6 wherein said shaft is provided with an axiallyaligned through slot adjacent said first end of said shaft for receivingsaid flat spring therein while enabling said spring legs to extendradially beyond said slot.
 11. A method of selectively attaching acutting device to a surgical handpiece comprising the steps of:providinga wrenchless collet having a first clamping surface member and a secondclamping surface member, said members being relatively movable between aclosed position wherein they are aligned such that a cutting device maybe held by said members and an open position wherein they are spaced anda cutting device may be inserted or removed therefrom; providing meansto hold said wrenchless collet either open or closed; providing a useraccessible means secured to said first clamping surface member to urgesaid first clamping surface member either toward or away from saidsecond clamping surface member; selectively opening said wrenchlesscollet by linearly pushing said user accessible means in a first lineardirection to move said first clamping surface member axially in onedirection; selectively closing said wrenchless collet by linearlypushing said user accessible means in a second linear direction to movesaid first clamping surface member axially in a direction opposite tosaid one direction.
 12. A method according to claim 11 wherein said useraccessible means is a shaft having opposed ends, said shaft secured tosaid first clamping surface member, further comprising the steps ofactivating said user accessible member by pushing said shaft in oneaxial direction or the other.
 13. A method according to claim 12 whereinsaid means to hold said wrenchless collet comprises a bi-stable springmeans for providing in one bi-stable state an axially directed firstforce in a first direction to hold said collet either open or closed andfurther comprising the step of exerting an axially directed second forcein a second direction to overcome said first force to place said springmeans in the other bi-stable state.